A novel solid-state electrochromic supercapacitor with high energy storage capacity and cycle stability based on poly(5-formylindole)/WO3 honeycombed porous nanocomposites

Novel honeycombed porous poly(5-formylindole) (P5FIn)/WO3 nanocomposites are successfully prepared through combining hydrothermal synthesis and electrochemical polymerization. The morphology and structure of prepared P5FIn/WO3 nanocomposites are characterized by SEM, TEM, FTIR, Raman spectra, XRD and XPS. Due to the synergistic effect of P5FIn and WO3, the prepared nanocomposites exhibit excellent electrochemical, electrochromic, supercapacitive properties and cycle stability. The areal specific capacitance of the nanocomposites is 34.1 mF cm−2. After 5000 cycles charge and discharge, the nanocomposites can still maintain 93% of its initial capacitance value. A high coloration efficiency (137 cm2 C−1) is also shown when the nanocomposites reversibly switches among dark green, yellow and yellow green. The fabricated electrochromic supercapacitor based on P5FIn/WO3 and poly(3,4-ethylenedioxythiophene) (PEDOT) shows high specific capacitance (10.38 mF cm−2), high coloration efficiency (627 cm2 C−1) and stable cyclic stability up to 5000 charge/discharge cycles. By means of color change and transmittance change during the charging and discharging process, the smart visual monitoring of the energy storage state of the supercapacitor is realized. After charged, the supercapacitor can light up a LED, indicating good practical application ability. The fabricated electrochromic supercapacitor may have practical application in electronics fields due to its high energy storage capacity and cycling stability.